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RGB/YPbPr Intellivision Thoughts


the_crayon_king

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10 hours ago, Icelvlan said:

Are you able to post a picture of what I should be bridging/removing for a genesis 2 cable?

The other option is to remove all attenuation from the cable. I have a Genesis 2 style scart cable configured like this and use it for other mods like the Colecovision RGB board.

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On 2/3/2021 at 12:04 AM, Icelvlan said:

are you able to add black borders around to make it 240p or is that just something an FPGA can do?

 

On 2/2/2021 at 8:25 PM, the_crayon_king said:

Well I am pretty sure I can make sync do whatever I want now. That has been true for some time.

All my personal devices work with this. I would need something that should work with this but doesn't then I can test the various different syncs I have made. IMO there is no point in fixing sync if it already works because of the room the fix takes up.

 

Once again AFAIK line doublers not supporting this is not an issue with the mod kit but an issue with linedoublers. It is just too low a resolution. If someone has information contrary to that then I have yet to hear it. I could eventually scale the output but that would be a whole 'nother project.

 

 

With the coloured borders it looks like 240 lines of resolution.  How many lines are you getting?

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  • 2 weeks later...
On 2/20/2021 at 8:59 PM, Icelvlan said:

Any updates on sync?

 

Somebody, somewhere had this working with an LTO through a Retrotink 2X. They were running the old version of code (which I lost).

Since getting this news I have ordered a Retrotink 2X and if the current code doesn't run with that scaler I will remake that older code. (I know the gist of what I did it wasn't complex).

 

That would mean so far these would work on CRTs (through YPbPr), Retrotink (tentative), that crappy HD scaler, and the XRGB.

 

That would just leave the OSSC and maybe the HD Retrovision. If the Retrotink can work with this but not the OSSC then something should probably be done on the OSSC end. I think it has settings for PLL or something which might do something.

 

TLDR

I CAN make sync do whatever I want but if I can get the retrotink to work then I will probably leave it alone. There are about a dozen reasons I do not want to change the board design to implement that complete sync reconstruction. I just wanted to work out how it could be done.

 

Just a note to be clear I was off on some tangent about trying to make this work on that crappy scaler again since it stopped at some point; but it only stopped because that scaler needs a 5V ref not because of the code changes. That whole ordeal might confuse people so this is just clarification.

 

 

On 2/12/2021 at 10:11 AM, mattyv316 said:

The other option is to remove all attenuation from the cable. I have a Genesis 2 style scart cable configured like this and use it for other mods like the Colecovision RGB board.

Just don't jumper those pads (like you would do on the colecovision RGB) on this board those resistors are pulldown resistors so you just need to remove them.

If you bridge that connection you will not get video and probably fry the DAC.

 

 

On 2/12/2021 at 10:58 AM, mr_me said:

 

With the coloured borders it looks like 240 lines of resolution.  How many lines are you getting?

 

Is the line count just the hsync pulses?

I am not sure I have a way to give a specific number.

I had the Hsync pulses as:

 

Quote

I confirmed the width between vsync pulses is 16.6ms

16.6ms = 16600us

16600/if 63.5us = 261 - 9 missing pulses = 252

16600/if 64us   = 259 - 9 missing pulses = 250

So my lines were between 261 and 250 which is quite a margin. I can't count the lines I have to use the distance between each vsync pulse and then the distance between each sync pulse.

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I posted my results from the board that had the old version of Crayola's code (prior to Jan 11 2021) HERE

The only other thing I would add to the post in the link is that I do not have the video drop out for a lengthy amount of time while browsing the games on LTO. Small flashes here and there, but not like I do on my console(s) that have the Fed K board.

A current revision board is on it's way now. I will install that and see how that compares. I am not expecting OSSC to work, but I would like to see how the new board revision performs with the 2x Scart and Rad2x Genesis 2 cable.

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On 2/25/2021 at 11:35 AM, mattyv316 said:

I posted my results from the board that had the old version of Crayola's code (prior to Jan 11 2021) HERE

The only other thing I would add to the post in the link is that I do not have the video drop out for a lengthy amount of time while browsing the games on LTO. Small flashes here and there, but not like I do on my console(s) that have the Fed K board.

A current revision board is on it's way now. I will install that and see how that compares. I am not expecting OSSC to work, but I would like to see how the new board revision performs with the 2x Scart and Rad2x Genesis 2 cable.

 

I got my retrotink 2X today and can confirm the current code plays fine on real games via the Retrotink 2X.

I have confirmed the XRGB, the HD scaler (just google HD SCART scaler), my CRTs and the Retrotink 2X work with the current revision of code.

So now I just need a LTO, OSSC, and HD Retrovision.

 

I will have to wait till you confirm if the new code works the same with the LTO. Thanks for testing this BTW.

 

If it does I can figure out why maybe. I am assuming the LTO is doing something with sync during transitions.

The difference might come down to 1XX01 (mine) VS 1XXX1 (others). Otherwise it would be the sync pulses I added into VSYNC but looking back at those pulses they shouldn't be helping things (which is why I removed them).

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If the retrotink can work and it is a line doubler and the OSSC cant and its a line doubler then the only conclusion I can draw would be that the OSSC needs to change its code. The changes where I reconstructed sync entirely would need a different board design not just code changes.

 

Anyway, I would have to get a hold of an OSSC and see if it can't be done in a simpler way,. if it can be done in a simpler way then maybe that could fit and be flashed.

 

I wouldn't buy one if I only had an OSSC or HD retrovision. It is doubtful that it will work. Of course I am still surprised that the Retrotink worked so who knows... Perhaps adjusting the PLL settings on the OSSC would be enough? I would feel more comfortable getting one and confirming things rather than sending them out with the onus that "maybe it will work on the OSSC". I would rather say that it does not work on the OSSC.

Edited by the_crayon_king
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20 hours ago, the_crayon_king said:

 

I got my retrotink 2X today and can confirm the current code plays fine on real games via the Retrotink 2X.

I have confirmed the XRGB, the HD scaler (just google HD SCART scaler), my CRTs and the Retrotink 2X work with the current revision of code.

So now I just need a LTO, OSSC, and HD Retrovision.

 

I will have to wait till you confirm if the new code works the same with the LTO. Thanks for testing this BTW.

 

If it does I can figure out why maybe. I am assuming the LTO is doing something with sync during transitions.

The difference might come down to 1XX01 (mine) VS 1XXX1 (others). Otherwise it would be the sync pulses I added into VSYNC but looking back at those pulses they shouldn't be helping things (which is why I removed them).

The new board showed up yesterday, and I was able to install it today. I replaced a Fred K board in my INTV III and the results are the same as the first board I installed in my SSVA that had your code prior to Jan. 11 2021. 

The mod works with the RetroTink 2x SCART (as you mentioned), Rad2x (Genesis 2) cable, and the cheap Amazon scaler. These were all tested with the LTO and did NOT have any problems browsing the menu. LTO also performed as it should loading and playing games.

I did not get any sync or signal through my OSSC.

One other thing to note is that when I tested the 2x SCART, I tested both directly to the 2xSCART and through a GScartSW. Both worked great.

No new pics as the output is the same as my previous posted pics of RT 2X SCART and Rad2x.

I would love to get RGB through OSSC for the INTV, but I think having a working solution with RetroTink products is a very good option to have. Thank you for providing a board that enables this as an option.

 

 

 

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7 hours ago, mattyv316 said:

The new board showed up yesterday, and I was able to install it today. I replaced a Fred K board in my INTV III and the results are the same as the first board I installed in my SSVA that had your code prior to Jan. 11 2021. 

The mod works with the RetroTink 2x SCART (as you mentioned), Rad2x (Genesis 2) cable, and the cheap Amazon scaler. These were all tested with the LTO and did NOT have any problems browsing the menu. LTO also performed as it should loading and playing games.

I did not get any sync or signal through my OSSC.

One other thing to note is that when I tested the 2x SCART, I tested both directly to the 2xSCART and through a GScartSW. Both worked great.

No new pics as the output is the same as my previous posted pics of RT 2X SCART and Rad2x.

I would love to get RGB through OSSC for the INTV, but I think having a working solution with RetroTink products is a very good option to have. Thank you for providing a board that enables this as an option.

 

The GScartSW and other things that regenerate sync may have issues with this but it might be on a case by case basis.

 

I don't know how Fred K did his board but LTO stability might come down to the 1XXX1 vs 1XX01 thing. I know many of you don't know what I am talking about but that is the only thing I can think of. We are using the same CPLD so it is interesting that compatibility with the LTO is different. That difference might be relevant to other Intellivision RGB kits as well. A solution might be to invert V2 and use a triple NAND so V5, V1, and inverted V2 (for non-programable kits) and to use the four (really three) sync bits inside of 1XX01 (10001 [this is not active], 10101, 11001, 11101) for programmable kits. The theory I have is that 1XX11 or 10001 is triggering on other kits when using the LTO menus. These combinations would normally be inactive but if the kit is only using V5 and V1 to trigger sync then then this is being seen as a sync pulse. I cannot guess further without actually having a LTO.

 

Fixing compatibility on the OSSC is on the docket but it is probably not something I can do on these current PCBs. It would be better if the code for the OSSC was altered to account for whatever broken sync this console is putting out. I will eventually get an OSSC and tweak around with it till I get video.

 

Thanks again for testing.

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  • 2 weeks later...

I received a new board on Monday but won't be able to install and test it for a bit as my current workload on console services is taking priority for the moment. My plan is to just wire it up straight as is and see what I get. If the image is too dark, then I will likely remove the 75Ω on the outputs.If not, then I will let you know there as well.

 

 

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13 hours ago, -^CrossBow^- said:

I received a new board on Monday but won't be able to install and test it for a bit as my current workload on console services is taking priority for the moment. My plan is to just wire it up straight as is and see what I get. If the image is too dark, then I will likely remove the 75Ω on the outputs.If not, then I will let you know there as well.

 

 

 

I am tempted to create the conditions you have over here and see what happens. I would expect it to be darker.

I have ran these without a 75 ohm pulldown and instead a 75 series before when I made a 3DO RGB kit. I didn't notice anything weird but then again I am not a 3DO guy.

 

The kit should tolerate resistors inside of the cable up to about 470 ohms. That is an upper limit though. Anything higher will be below 300mv p-p (bad).

 

At any rate I am curious to see if you can get it working. All I know is I tested it on everything I have over here and it all looked good.

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On 3/10/2021 at 11:23 PM, the_crayon_king said:

 

I am tempted to create the conditions you have over here and see what happens. I would expect it to be darker.

I have ran these without a 75 ohm pulldown and instead a 75 series before when I made a 3DO RGB kit. I didn't notice anything weird but then again I am not a 3DO guy.

 

The kit should tolerate resistors inside of the cable up to about 470 ohms. That is an upper limit though. Anything higher will be below 300mv p-p (bad).

 

At any rate I am curious to see if you can get it working. All I know is I tested it on everything I have over here and it all looked good.

The second board has been installed and it does work. But just like Yannick's it only works through the SCART to HDMI converter box. Anything else just states No Sync. That is literally what the OSSC says when I try it is No Sync although my SCART switcher does detect the signal. It is slightly more muted palette compared to Yannick's but I'm not sure that is a bad thing at all. 

 

Here is a direct capture from the SCART to HDMI converter without audio as I was only interested in the video itself. Nothing was changed on the RGB at all. It is as it arrived in the mail installed.

 

 

 

 

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8 hours ago, yell0w_lantern said:

I'm just planning on running this through a Retrotink 2x Pro using RCA component cables. Do I need to make any modifications? I think sync on green, right?

 

Set the pad labeled "COL" for YPbPr. You could also put it on a switch with the through holes labeled "YPbPr"

SOG is sync on green which is for RGB.

 

I also haven't tried this on a 2X pro. The YPbPr here was for using on a CRT., it still will probably work but idk.

 

 

@-^CrossBow^- I think the idea is this mod kit and the others should look pretty close. I could use a string of resistors and get similar results whilst saving tons of (code) room the difference in colors is negligible imo but the goal of this kit is kind of different from the others as well. So the biggest difference AFAIK is the color accuracy (negligible imo), color adaptability (extra palettes), functionality (this kit can work on other consoles with different codes installed), and lastly SOG and YPbPr. Both YPbPr and SOG have insofar been unused (by others) but they are great if you need them.

 

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22 minutes ago, the_crayon_king said:

 

@-^CrossBow^- I think the idea is this mod kit and the others should look pretty close. I could use a string of resistors and get similar results whilst saving tons of (code) room the difference in colors is negligible imo but the goal of this kit is kind of different from the others as well. So the biggest difference AFAIK is the color accuracy (negligible imo), color adaptability (extra palettes), functionality (this kit can work on other consoles with different codes installed), and lastly SOG and YPbPr. Both YPbPr and SOG have insofar been unused (by others) but they are great if you need them.

 

Maybe I need to play with component output. Do I just have to bridge the pads for it and then wire the outputs to Red,Green, and Blue with a common ground to get that? I've not wired up component before so that would be new to me. But I'd be curious to see if it might work on my Extron since it does accept component input.

 

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58 minutes ago, -^CrossBow^- said:

Maybe I need to play with component output. Do I just have to bridge the pads for it and then wire the outputs to Red,Green, and Blue with a common ground to get that? I've not wired up component before so that would be new to me. But I'd be curious to see if it might work on my Extron since it does accept component input.

 

In my experience CRTs are usually alot more forgiving with sync (but just like with these scalers I can only confirm what I have works). Keep in mind that it will probably not work with a newer TV and if it did work it would be subpar (flatscreen typically cannot scale very well).

 

You just need to either permanently bridge the COL pin (this will hard set YPbPr as always on). Or you can use the provided SPDT switch and run wires from the YPbPr through holes. If you just set one wire on the middle leg and the other to either other leg then one position (closed) will be YPbPr and the other (open) will be RGB.

 

Once one of those are bridged R = Ry, G = Y, and B = By. They should have a common ground., just like RGB has a common ground. 

 

Additionally, I had better results when using capacitors (220uf) on YPbPr. This was only looking at the waveform I don't think it had any impact on visual results but might be something to consider. 

 

The reason the capacitors aren't installed by default is because if people need to have capacitors on their outputs they probably already have capacitors in the cable and 2 capacitors in series is bad (cuts the capacitance in half ?).

As is there shouldn't be any appreciable DC shift but I don't remember looking into it. I don't necessarily understand why using a capacitor was giving me cleaner transitions (over YPbPr) anyway so take all of this with a grain of salt. 

 

--------------------------------------------------------------------------------------------------------------

RGB mode may work on the HD retrovision cable if you use sync (from the RGB kit) instead of composite from that other kit. The composite signal's sync coming from that composite kit you have would probably look really broken and is probably unusable by the HD retrovision.

 

I am assuming the HD retrovision has a sync stripper they probably chose to use composite because it is already present on every console anyway and using the LM1881 for example would give them a known voltage for mixing RGB+S into YPbPr. I am making alot of assumptions here but those are my thoughts on the matter. I looked into making something like that before with 4 op amps and a sync stripper; It would work but I don't know if that is what they are doing at all.

--------------------------------------------------------------------------------------------------

On another note any consoles that has RGB and Y can get YPbPr very easily. All it takes is mixing RGB into R-Y and B-Y since you already have Y. Tim Worthington's YPbPr kit can be used to do this. I have built my own circuit to do it and have it installed in most of my consoles (since I typically only play through CRTs).

 

Some of the consoles that didn't have Y I instead used a BH7236AF and a clock to give me Y and then used the same circuit from there. Maybe this is something I could make into a product for other people.

Edited by the_crayon_king
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Actually I've tried to use HDRetrovision cables using Sync in the past and it doesn't work. I did make it work using C-sync from a Genesis but had to attach a resistor and capacitor in series off the c-sync and route to that the composite input for the HDR cables to actually work. So normal sync they won't ...well ...sync with.

 

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10 minutes ago, -^CrossBow^- said:

Actually I've tried to use HDRetrovision cables using Sync in the past and it doesn't work. I did make it work using C-sync from a Genesis but had to attach a resistor and capacitor in series off the c-sync and route to that the composite input for the HDR cables to actually work. So normal sync they won't ...well ...sync with.

 

 

I looked at the PCB for the HD retrovision (dreamcast) and can now say I have no idea what they are doing.

I can see a way to covert from RGB with like 3 ics and a string of resistors.

Theirs looks to be so much else going on.

 

I suppose if you are trying to get the sync to appear like a composite signal all you would need is to add a 220uf capacitor and add a 500 ohm resistor. That would be around 300mv p-p which should be whatever it is looking for anyway. This is for this specific kit. Other consoles/kits IDK about.

 

I need to make that circuit I am talking about and have like a head to head with the HDR to see if there is any appreciable difference. Mine certainly won't be any better but I am curious how much worse mine would be comparatively.

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9 hours ago, the_crayon_king said:

I suppose if you are trying to get the sync to appear like a composite signal all you would need is to add a 220uf capacitor and add a 500 ohm resistor. That would be around 300mv p-p which should be whatever it is looking for anyway. This is for this specific kit. Other consoles/kits IDK about.

That is exactly how I got it working. I attached a 460Ω resistor as that was likely what I had on hand and a 220µf 6.3v cap in series from off the C-sync line off the Genesis AV output and routed that to the composite input pin on a 32x AV out. We are getting off topic here, but this was needed because an s-video upgrade had been added to this 32x. But the s-video mod on the 32x requires you to kill the composite circuit to prevent inteferrence on the s-video from the shared luma signal. Naturally doing this meant that HDRetrovision cables wouldn't work from a 32x that has been s-video modded. But doing the above I was able to restore a sync signal from the C-sync line that the HDR cables would then accept and allow them to work.

And yes, my understanding is that HDR has a lot of magic under the hood of that little black box off their cables. When they work they look fantastic.

 

But I did try something similar using the sync line and the HDR cables still didn't work either your kit or Yannick's.

 

I'm going to go ahead and purchase a Retrotink2x SCART although I honestly don't need one, just to have on hand to test with so I can at least tell potential clients that it is a device known to work with the RGB kit for the Intelly. The Tink2x Scart is at least something that can still be bought for a semi reasonble price, unlike the FM.

 

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@-^CrossBow^- My guess is they are using an alternative method to strip sync so that they don't need to use a dedicated sync stripper. I wouldn't do that personally but I am sure the designer knew what they were doing and had their reasons.

 

The retrotink 2X scart has become my recommended way to play the Intellivision in lieu of a CRT.

 

I think the Intellivision code/board is stable enough for me to venture toward other projects.

I will probably be working on the Aquarious or the O2 next both of which already have the main code complete.

 

I also need a logic analyzer to develop more interesting things.

 

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  • 2 weeks later...

Okay, I got my Tink2x SCART in the mail today. It does work with your kit, however, I get a TON of screen blank outs while playing. On some games it might not be too big a deal, but on anything arcade like it simple won't do because it will cut out completely and take a few seconds to come back. It might stay up and running for several minutes without issue and then blank out a few sec or it might do it every time something particular happens in the game.

 

As an example, Thunder Castle is one of my favorites on the Intellivision. Every time a new enemy comes onto the screen, it will flash the screen and that will kill the video signal for a few seconds.

 

So the only way for me to play with a fully stable picture is by using the cheap SCART to HDMI converter.

 

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